Composite reinforcement for support columns

ABSTRACT

A process for reinforcing a load supporting structure including placing a first layer of at least one distinct pre-cured composite piece around the structure, applying adhesive between the piece and the structure, exerting pressure until the adhesive cures, wherein the piece is performed with a shape complementary to the structure, placing at least one additional layer of at least one distinct pre-cured composite piece around the structure and the first layer, and applying an adhesive between the layers.

BACKGROUND OF THE INVENTION

The present invention relates to support columns, such as concretesupport columns for bridges, and, more particularly, to reinforcement ofsuch columns with a composite material.

Support columns, such as bridge supports and supports in parkingstructures, can occasionally experience forces beyond the forces forwhich they were designed. This has happened a number of times duringearthquakes. The results have been catastrophic, with the collapse ofbridges and other structures, loss of life and the loss of use of majorhighways for many months, and even years. The cost of rebuildingcollapsed structures like bridges is so high that sometimes thestructures are not rebuilt.

Concrete bridge columns are typically 4 to 8 feet in diameter and 20 to60 feet high. In an earthquake, the ground shifts not only laterally,but vertically. The lateral shift causes a failure at the column base orin the mid-column because of the inertia of the upper bridge structurebeing at rest while the lower structure shifts laterally. In the case ofthe 1994 San Fernando Valley earthquake, the ground also moved up from athrust fault, which caused the columns to fail in the middle versus thelower sections, where they failed in the 1989 Loma Prieta earthquake.

Pre-1971 bridge columns in California had a sufficient amount ofvertical steel, but only had circular reinforcing lap splice barsapproximately every 12″. In the 1971 Sylmar earthquake, the 1989 LomaPrieta earthquake, and the 1994 San Fernando Valley earthquake, many ofthese columns exploded because of the forces, either from the groundmoving up in the earthquake, or from the inertia of the bridge deckcollapsing down. This caused the columns to explode radially outward ina pear-shaped fashion. More-recently constructed columns have a completecirumferential reinforcement cage defined by circumferential reinforcingbars spaced approximately on one-inch centers, rather than on thepreviously used one-foot centers.

Some concrete bridge columns which were already reinforced with embeddedsteel reinforcing bars have been retrofitted with steel jackets. Thesteel jackets typically have a thickness between ⅜″ to 1 inch, dependingupon a variety of conditions, including soil conditions, the originaldesign of the column, the height of the column, the amount of load thecolumn carries, etc. In order to retrofit existing columns withadditional reinforcement, steel jackets made of semi-cylindricalsections are placed around the outside of the columns, and the sectionsand jackets are welded together to form adequate confinement. A drawbackwith the steel jackets is that they must fit as tightly as possible,even though the concrete columns are not always precise in diameter. Inorder to accomplish this, the columns are individually measured andthose measurements are used to fabricate steel jackets of approximatelythe same diameter. The semi-cylindrical jacket sections are slightlyoversized, for example ⅛″ to ¼″ oversized in radius. After the jacketsare welded in place, they are pumped with an epoxy grout to serve as amedium to transfer from the concrete column to the steel jacket theloads imposed on the column. Sometimes a concrete slurry is injectedbetween the steel jacket and the column, because of the difficulty infitting the jacket to the column. However, there is shrinkage with theinjected concrete and, therefore, there is inadequate load transferbetween the column and the jacket. Furthermore, the steel jackets arevery heavy and cumbersome to install, even with the aid of power cranes.Moreover, skilled workers, e.g., welders, are required to install thesteel jackets, and the jackets are subject to corrosion and requiremaintenance. Space between the steel jackets and the concrete column ispumped with a pressuring grout to maintain adequate load transfer fromthe column to the jackets. However, because the column may often becoated with a significant amount of residue and because the steel jacketmay have rust on it, the bond between the two load transfer surfaces isoften insignificant.

The use of a resin pre-impregnated semi-cured material using carbonfibers or glass fibers or KEVLAR fibers and the use of a wet lay-upsystem involving high strength fibers and wet resin are currently beingpursued. In the wrapping of columns with pre-impregnated tape, an entiremachine must be brought to the job site. The use of the machine to wrapthe columns can be very difficult in confining situations where thecolumns are placed very near walls.

Other support columns, which are commonly made of wood, such as utilitypoles, wharf pilings and bridge supports, occasionally experienceexceptional forces, such as in winds or earthquakes. They also sufferfrom general wear and tear. Furthermore, many wooden utility polestreated with creosote experience dry rot in their lower portions.

SUMMARY OF THE INVENTION

By the present invention, apparatus is provided which reinforces supportcolumns to withstand exceptional loads, without having the drawbacks ofpreviously known devices.

A column reinforcement device is provided which is easy to install inthe field with unskilled labor. The column reinforcement device can beinstalled without heavy machinery or heavy tools. The columnreinforcement device is premeasured to be the correct diameter, lengthand thickness for the column. The preformed nature of the device permitsit to be precisely premeasured as to width, length and diameter for theparticular column on which it is to be used. The appropriate dimensionscan be determined as a result of testing in a laboratory. Theelimination of the need for calculating, measuring or cutting in thefield permits the composite column reinforcement to be installed by anunskilled worker and in severe weather conditions.

The column reinforcement comprises preformed, precured composite membersto reinforce the column against failure in earthquakes and otherextraordinary events. The device comprises a large plurality ofbidirectional continuous, lightweight, high strength, electricallynon-conductive nonmetallic fibers extending parallel to one another, anda resinous material encapsulating the fibers.

Because of the uniformity and diameter of bridge column height, thecomposite column reinforcement members of the present invention are wellsuited to high volume manufacture and ease of installation in the fieldwith semi-skilled labor.

By the present invention, apparatus is provided which reinforces supportcolumns to withstand exceptional loads, without having the drawbacks ofpreviously known devices.

Concrete is brittle. It has limited ductility.

The composite column reinforcement members according to the presentinvention greatly increase ductility and confinement for concretecolumns. The composite column reinforcement members confine the concreteand prevent the outward expansion or spalling of concrete. If theoutward expansion or spalling can be prevented, then the column will beadequate to support the bridge load, even if the concrete is pulverizedby the compressive forces from an earthquake.

Because the structural columns are subject to side-to-side loads, notonly vertical acceleration and compression, longitudinal fibers are inthe reinforcement members to provide an adequate side-to-side loadreinforcement.

By encapsulating the concrete columns with the composite reinforcingmembers, there is nowhere for the concrete to go if the concrete shearsor compresses and turns in fact to rubble, because its outercircumference is contained. Consequently, the column and the structureit supports remain intact. In contrast, in an unconfined structure, theacceleration of the column caused by the forces of the earthquake causethe column to either be crushed or to be sheared and the outer portionsof concrete to spall off. With this spalling off of concrete, thediameter of column is reduced, its ability to support an upper structureis decreased, and the column fails, along with the upper structure. Thecomposite reinforcing members are intended to be used with concretecolumns containing steel reinforcing bars, as well as with columns whichdo not contain reinforcing bars.

The composite column reinforcement devices can take the form of coilbands having a plurality of concentric elastic convolutions, or jacketsdefining almost complete cylinders except for a small, axially extendinggap.

The composite reinforcement members of the present invention are fixedto concrete columns by a high-elongation adhesive, such as a urethaneadhesive, which has an affinity for both the composite and the concrete.

Based on the use of 1,000 psi adhesive, a 61′ diameter column with a 5′high jacket would have about 13 million pounds of shear strength,thereby making the jacket integral with the concrete column.

The composite column reinforcement members are light enough to be veryeasily handled by two installers. A 6′ diameter composite reinforcementjacket, 5′ high, and ⅛″ thick weighs approximately 125 pounds. Thecomposite reinforcement members are made relatively thin e.g., so that,if additional reinforcement is required at the base of the column, themiddle or the top of the column, additional reinforcement members cansimply be placed over the outside of previously applied members, therebymaking the system as “application friendly” and adaptable as possible inthe field.

Also, because of the physical flexibility of the composite material,reinforcement members in the form of jackets, or sleeves, can be stackedone inside another, possibly stacking as many as ten jackets in thismanner for easy transport with minimal space requirements. With theirresilience, the jackets return to their original shape when unpacked atthe jobsite.

Because the composite jackets are produced in a factory under controlledconditions, the densities of the filaments and resin is very precise,and the mechanical properties are very uniform, especially compared tofilament and resin systems which are laid up wet in the field. Thedimensions can be checked, the fiber reinforcement content can bemeasured through resin burnoff or other laboratory tests, and,therefore, a high degree of uniformity can be obtained.

The skill level required of installers is significantly lower than forsteel jackets, which must be welded in place. Basic laborers can applythe composite column reinforcement members of the present invention onfreeways, bridges or other structures.

By reinforcing a concrete column with the composite reinforcing membersof the present invention, the deformation and the ductility of thecolumn are significantly increased. The present invention confines theconcrete from spalling off and increases the ductility of the columnduring bending by the use of a very simple hand-applied system.

The composite reinforcing jackets rely on the strength of the filamentsand their bidirectionality, in that the longitudinal fibers support thecolumn from bending or shearing sideways, while the circumferentialfibers support the column from failing in a radial or circumferentialdirection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a reinforced support column according tothe present invention supporting a highway overpass;

FIG. 2 is cross section of the reinforced column taken along the line2—2 in FIG. 1;

FIG. 3 is a perspective view of a first embodiment of a compositereinforcement member according the present invention;

FIG. 4 is a schematic view of a tape of bidirectional fibers used inmaking the composite reinforcement member of FIG. 3;

FIG. 5 is a perspective view of an assembly of composite reinforcingmembers of a second embodiment according to the present invention asfabricated;

FIG. 6 is a schematic view of a process for making the assembly ofcomposite reinforcement members of FIG. 5;

FIG. 7 is a view of the assembly of composite reinforcement members, inan unfinished condition, made by the process of FIG. 6;

FIG. 8 is a perspective view of a reinforced support column according tothe present invention, using a plurality of the reinforcement members ofFIG. 5 to support a highway overpass;

FIG. 9 is a cross section taken through a support column reinforced witha plurality of the reinforcement members of FIG. 5;

FIG. 10 is a schematic representation of layers of reinforcement membersarranged around a support column;

FIG. 11 is a schematic cross section through a support column reinforcedby square reinforcement members according to the present invention;

FIG. 12 is a schematic representation of the forming on a mandrel of athird embodiment of a composite reinforcing member according to thepresent invention; and

FIG. 13 is a graph of the performance in a splitting shear test of bareconcrete test cylinders and concrete test cylinder reinforced withcomposite reinforcement members according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As can be seen from FIG. 1, a composite reinforced support columnaccording to the present invention, which is designated generally by thereference numeral 10, is shown rising from a base 12 to support sections14 of a highway overpass 16. As can be appreciated from FIGS. 1 and 2,in this embodiment, the composite reinforcement is in the form of bands18-21 wrapped spirally, or helically, around a primary load-bearingmember 22, such as a concrete column. Such composite reinforcement bands18-21 are wrapped, one over the other, with the end of each band spacedaround the perimeter of the primary load-bearing member 22 from the endsof the other bands. The ends are normally spaced equally so that, forexample, where four bands are applied, one over the other, the ends ofthe bands are spaced by 90° around the perimeter of the primaryload-bearing member 22, as can be seen from FIGS. 1 and 2. Furthermore,the direction of the helix of alternate bands is reversed. Thus, theband 21 of FIG. 1 is wound counterclockwise, the adjacent underlyingband 20 is wound clockwise, and so on, such that a herringbone patternis present.

The first composite reinforcement band 18 is held fixed to the column 22by a layer of adhesive 24 extending over the entire inner surface of theband. Subsequent reinforcement bands 19-21 are wrapped around and fixedto underlying bands by additional layers of adhesive 25-27 extendingover the entire inner surfaces of the bands. Although the layers ofadhesive 24-27 may be different in thickness from the thickness of thecomposite reinforcement bands 18-21, they are shown in FIG. 2 as havingthe same thickness as the reinforcement bands for clarity ofillustration. The reference numerals 28-31 indicate the lower ends ofthe bands 18-21, respectively.

The adhesive is either a single or plural component adhesive system,which can be mixed in static mixers and pumped from drums. The adhesivecan be an expanding, moisture-activated adhesive, so that the adhesiveis not activated until water is applied to it by, for example, sprayingthe water. Catalyst is mixed with the sprayed water and, by changing therelative amounts of catalyst and water, the curing time of the adhesivecan be changed. Based on the resin-catalyst ratio of the adhesive, thecure time, or work time, can be changed dramatically. As an example,with a pre-heated urethane adhesive system, the work time can beapproximately 25-30 seconds with a low catalyzed plural componentsystem, or as much as 2 hours. The cure time on these adhesive systemsat ambient temperature is approximately 4-5 hours. Both one-componentand two-component adhesives are suitable for fixing the compositereinforcing members to the primary load-bearing members. Suitableone-component systems are available under the designations 22005 and22009, and suitable two-component adhesives are available under thedesignations 2U056 and 2U057, all from Swift Adhesives of Downers Grove,Ill.

FIG. 3 shows a composite reinforcement band 18 prior to its wrappingaround a column. The reinforcement band 18 comprises a coiled web 32 ofcomposite material having a rectangular transverse cross section and aplurality of concentric elastic convolutions including an innermostconvolution having an inner end 34, an outermost convolution having anouter end 36, and intermediate convolutions. The composite materialincludes a large plurality of bidirectional, lightweight, high tensilestrength, electrically non-conductive nonmetallic filaments or fibers 38and 40 extending parallel to one another in the web 32, the fibers beingencapsulated in a completely cured resin matrix. Each fiber 38 extendsthe entire length of the web 32, and each fiber 40 extends across theentire width of the web, at, for example, 90° to the fibers 38. Althoughthe parallel fibers 38, 40 are generally indicated in FIG. 3, byparallel lines 38 and 40, each space between adjacent parallel linesactually represents hundreds or thousands of fibers, each having, in thecase of glass fibers, a diameter of less than 0.001 inch (0.0025centimeter).

The resin matrix is applied to the fibers 38, 40 during manufacturingand prior to curing. With the resin in place and fully cured, thecomposite material is impervious to corrosion and most fluids and,thereby, protects the fibers 38, 40 and the portion of the column 22underlying the reinforcement band 18 from deterioration. Glass is asuitable material for the fibers 38, 40, and especially E-type glassfibers because they are relatively inexpensive. However, other fibers,such as fibers made of KEVLAR, carbon or polyester can also be used.Suitable resins are resilient when cured and, when they are cured in acoiled spiral configuration, they will return to the same configurationafter being uncoiled, once the uncoiling force is removed.

As can be seen from FIG. 4, the web 32 can comprise bundles, or rovings,of the fibers 38 and 40 in which rovings 42 of the transverse fibers 40extend alternately over and then under adjacent rovings 44 of the fibers38 as the fibers 40 extend from one side of the web to the other,thereby defining a woven material made of the fibers. As an alternative,the rovings of the fibers 38 and 40 are not woven, but instead thelongitudinal fibers 40 lie generally in one or more first planes, andthe transverse fibers 38 lie generally in one or more adjacent secondplanes. Stitching can be used with the unwoven alternative to hold thefibers 38 and 40 in rovings and to hold the fibers 38 in a 90° or otherpredetermined orientation relative to the fibers 40. Depending on theforces involved in the structure to be reinforced, the fibers in the web32 can be tri-directional rather than bidirectional. Thus, rather thanhaving some fibers 38 extend in one direction and other fibers 40 extendat 90° to the fibers 38, the fibers can extend in three differentdirections. For example, a first group of fibers can extend in a firstdirection, with a second group of fibers extending in a second directionat a 60° angle to the first direction and a third group of fibersextending in a third direction oriented at60° angles with respect toboth the first and second directions.

As can be seen from FIGS. 1 and 2, the preformed coil reinforcement band18 is put on in a helical fashion up the column 22 and then the bands19, 20 and 21 are put on in the same manner, each band comprising anadditional layer of reinforcement. The number and/or thickness of thebands employed depends upon the size of the column and the strengthrequirements. Where four reinforcement bands are used, the startposition of the second and subsequent bands 19-21 is indexed by 90°around the circumference of the column 22 relative to the subjacentband. The adhesive bonds the first reinforcing band 18 to the concretecolumn 22 and each overlying reinforcement band 19-21 to the adjacentunderlying band. The adhesive can be applied by various techniques, suchas with a spray gun. The preformed coil bands 18-21 can be applied usingtwo man-lifts, positioned on opposite sides of the column 22. Theinstallers start at the base of the column 22, applying the coilreinforcement band 22 by wrapping it up around the column in a helix.Once they reach the top of the column 22, the installers return to thebottom of the column and apply another layer, using another coilreinforcement band. An adhesive is used that cures anywhere in the rangeof from about 40° to about 100° Fahrenheit.

As can be seen from FIG. 5, in an alternate embodiment, thereinforcement devices according to the present invention can be in theform of sleeves or jackets which are placed around a primaryload-bearing member, such as the concrete column 22, and fixed in placeby the adhesive. FIG. 5 shows an assembly 46 comprising a plurality ofcomposite reinforcement jackets 48-51. Each of the jackets 48-51comprises the composite reinforcement material described in connectionwith the embodiment of FIGS. 1-3, including the longitudinal fibers 38,the transverse fibers 40 and the completely cured resin matrix. A layerof a conventional release film 39 (FIGS. 6 and 7) is interposed betweenadjacent jackets to facilitate the separation of the jackets 48-51 fromone another. The innermost jacket 48 is formed to have an inner diametersubstantially equal to the outer diameter of the column 22 to bereinforced. The innermost jacket 48 has an outer diameter which issubstantially equal to the inner diameter of the jacket 49. Similarly,the jacket 49 has an outer diameter substantially equal to the innerdiameter of the jacket 50, and the jacket 50 has an outer diametersubstantially equal to the inner diameter of the jacket 51. Although theassembly 46 of FIG. 5 contains four concentric jackets, other numbers ofjackets can be included in an assembly, depending on the size and weightof the jackets, and the ease with which they can be handled.

A typical width for a web of the fibers 38 and 40, or height or axialdimension for the jackets 48-51, is 5 feet, and a typical thickness foreach jacket is ⅛ inch. Furthermore, it is contemplated that jackets ofone-half the axial dimension of the primary jackets 48-51, that is, 2.5feet, will also be employed, as will be described hereinafter. Thejackets 48-51 extend most of the way, that is, about 358°, around thecircumference of the column 22, and a gap exists between thecircumferential ends 54 and 56 of the jackets. As a result of the gap,the jackets 48-51 can be expanded to extend around the column 22 orother primary load-bearing member. Due to their resilience, the jackets48-51 return to their original sizes and configurations around thecolumn 22 after the expanding force has been removed. Due to thepresence of a release film 39 between adjacent jackets, the jackets48-51 can be peeled away from one another easily. The compositereinforcing jackets 48-51 are lightweight, especially when compared tosteel jackets, and the sizing of the jackets 48-51 to nest within oneanother saves considerable space when the jackets are being transportedto a job site. As with the embodiment of FIGS. 1-3, where the forces inthe application warrant, the fibers in the webs of material in thejackets 48-51 can be tridirectional instead of bidirectional.

As can be seen from FIGS. 6 and 7, the assembly 46 of jackets 48-51 canbe made by bringing together and saturating a series of thin webs 58-62of filaments, such as a preformed tapes of woven fibers, for example, byfeeding the webs from spools 64-68, respectively, and through a bath 70of resin 72, squeegeeing off the excess resin with rollers 74 to definea wet impregnated strip of composite material, and winding the saturatedfilaments around a rotating mandrel 76 in a plurality of convolutions todefine a spiral band. The mandrel 76 has an outer diameter selected tocorrespond to the desired minimum inner diameter of the spiral,depending on the job application. Then, the resin is completely cured,thereby establishing an elastic set in the convolutions. In order thatthe resin-saturated fibers on the mandrel 76 remain in discrete layers,the release film 39 of MYLAR or other suitable material is applied tothe outer surface of the resin-saturated fibers, for example, from aspool 80 while the fibers are being wound around the mandrel. A similarrelease film or release coating is applied to the mandrel 80 itself sothat the assembly 46 of jackets can be removed. The curing isaccomplished under the normal curing conditions for the resin used. Forexample, for one suitable polyester isophthalic resin, an appropriateMEK peroxide catalyst can be added to the resin in the bath and then thedevice can be post-cured at a heat of 140° F. (60° C.) for about 2hours.

The thin webs 58-62 are brought together to form a complete web 82 ofdesired thickness. The thin webs 58-62, when dry, comprise layers in thecomplete web, but when the complete web 82 is saturated with resin, aunitary strip of composite material is formed. One of the thin webs canbe made, for example, entirely of longitudinally oriented fibers,another thin web can be primarily transverse fibers, another thin webcan be woven with 50% of the fibers longitudinal and 50% of the fiberstransverse, etc. A wide variety of fiber arrangements in the thin websis contemplated, the important consideration being that the complete webhas the desired amounts of fibers oriented in the desired directions. Ina typical complete web, 70% of the fibers are longitudinal and will beoriented circumferentially around the column, and 30% of the fibers aretransverse and will be vertical on a vertical column. The thin webs58-62 have a width substantially equal to the axial height of thejackets 48-51 to be formed. Each convolution of the complete web on themandrel 76 produces one reinforcing jacket. When the desired number ofconvolutions is achieved, the complete web is cut at the mandrel. Whenthe resin has cured, the spiral wound web on the mandrel 76 is cut downto the mandrel in the longitudinal direction, thereby producing theassembly 46 of jackets 48-51, with the cut forming the gaps between theends of the jackets, and a layer of the release film 39 between each twojackets to facilitate the separation of the jackets from one another atthe job site. The assembly 46 is removed in one piece from the mandrel,and the jackets 48-51 are individually marked so that they can beinstalled on a support column in the correct order and size sequence.

As can be seen from FIG. 7, the interleaving release film 39 is widerthan the web of fibers to prevent the resin from running around theedges and connecting with the resin of other layers. Prior to curing,some resin may run out onto the margins of the release film 39 andconstitute regions of flash 78 after curing. The flash 78 is trimmedoff.

In both the embodiment of FIGS. 1-3 and the embodiment of FIGS. 5-9, thefilaments 38 and 40 comprise on the order of.50% to 60% by weight of thecomposite reinforcing member, with the cured resin matrix comprising therest. In addition, the relative amounts of the fibers 38 extending inthe longitudinal direction, which will be circumferential on the column,and the fibers 40 extending in the transverse direction, which will bevertical on a vertical column, can be adjusted according to the forcesto be encountered in the primary load-bearing members to be reinforcedby the composite reinforcement devices according to the presentinvention. For example, in one application, 50% of the fibers can befibers 38 extending in the longitudinal direction and 50% can be fibers40 extending in the transverse direction. In another application, 90% ofthe fibers can be fibers 38 extending in the longitudinal direction and10% of the fibers can be fibers 40 extending in the transversedirection. Of course, many other relative amounts of fibers arepossible. Suitable resins for the matrix include vinyl ester resins andisophthalic polyester resins. A suitable vinyl ester resin is availableunder the designation Atlac 409 and a suitable isophthalic polyesterresin is available under the designation 33434, both from ReichholdChemical Company of Chicago, Ill. The jackets 48-51 are, for example,approximately 5′ in height and equal to the diameter of the column.Concrete columns commonly have diameters of 3, 4, 5, 6 and 8 feet. Theurethane adhesive systems which can be used with the present inventiondevelop a shear strength of between 1,000 psi and 2,000 psi. At 1,000psi, it is calculated that there is 13,376,400 lbs. of adhesive strengthto prevent any shearing between a 6 foot diameter concrete column and a5 foot high jacket.

During installation, adhesive is applied to a column and/or to jacketslike the jackets 48-51, and the jackets are spread apart at their gapsand placed around the column. As can be seen from FIG. 9, in order toprevent a gap from creating a weakness in the overall reinforcement, asecond jacket 80 is placed around a first jacket 82, with the gap 83 ofthe second jacket positioned 180° around a column 84 from the gap 85 ofthe first jacket. If the forces involved require third and even fourthlayers of reinforcement, a third jacket 86 can be placed around thesecond jacket 80, with its gap 88 positioned 90° around thecircumference of the column 84 from the gap 85 of the first jacket. Thegap 90 of a fourth jacket 92 is positioned 180° around the circumferenceof the column 84 from the gap 88 of the third jacket 86. A layer 94 ofadhesive is interposed between each jacket, as well as between the firstjacket, as well as between the first jacket 82 and the column 84.

In order to avoid a possible weak joint created with the arrangement ofthe jackets one on top of the other along the height of the column 84,the boundaries between adjacent jackets are staggered from layer tolayer. With reference to FIGS. 8 and 10, the first jacket 100 of thefirst layer has a first height, for example, 5′. The first jacket 102 ofthe second layer has a height which is one-half the height of the firstjacket 100 of the first layer, that is, 2.5 feet. The first jacket of athird layer (not shown) is 5′ in height, and the first jacket of afourth layer (not shown) is 2.5 in height. This arrangement allows foroverlap of the jackets of adjacent layers and staggered joints onadjacent layers, thereby avoiding any significant weakness in thereinforcement in certain horizontal or vertical planes. The jacket 100and additional jackets 104, 106, 108 and 110 in the first layer all abutone another at horizontal boundaries which are staggered axially withrespect to horizontal boundaries between jackets 102, 112, 114, 116 and118 in the second layer. This is accomplished by the use of thehalf-height jacket 102 at the bottom of the second layer. The otherjackets 112, 114, 116 and 118 of the second layer are of full height.The top jacket 110 of the first layer is half height. The gaps 120-124of the sleeves 100, 104, 106, 108, and 110, respectively, are spacedcircumferentially around the column from one another and also from thegaps 126-130 of the sleeves 102, 112, 114, 116 and 118, respectively, ofthe second layer. In FIG. 10, the vertical axis represents the height upthe column in feet, and the horizontal axis represents the positionaround the circumference of the column in degrees.

The jackets provide a high degree of flexibility in application, so thatthe needed reinforcement can be applied easily in varying amountsrequired in specific areas of a column, wherever needed. Thus, becauseof the stresses imposed at the top of the column and the bottom of thecolumn where they contact either the supported roadway or the base aregreater than in other areas of the column, additional composite columnreinforcement can be placed in these locations. For example, if only ahalf-inch thickness of reinforcement is required at the middle of acolumn and an inch thickness is required at the base, then four more ⅛″layers of composite column reinforcement would be placed at the base ofthe column.

Although the jackets were cylindrical in the example given above, thejackets can be formed in other shapes to have an interior surface whichis complementary to a support column. For example, the jackets can beformed in a hexagon, octagon, oval and rectangle, including a square. Ascan be seen from FIG. 11, for a column 132 having a square crosssection, composite jackets 136-139 having gaps 140-143, respectively,are square in shape to fit around the column. A layer 144 of adhesive isinterposed between each two of the jackets, as well as between thejacket 136 and the column 132.

Wood utility poles are. typically 12″ to 18″ in diameter and 30′ to 80′high. A composite reinforcing jacket according to the present inventionwhich is made to the diameter of a utility pole is typicallyapproximately 5′ to 6′ in height and approximately 12″ to 18″ indiameter. For a retrofitting on a utility pole in service, a hole is dugaround the pole, giving approximately 6″ of clearance on all sides. Dirtadhering to the pole is removed from the pole and the pole coated withthe urethane or other suitable adhesive system with bacteria andmicro-organism inhibitors. The jacket is opened up at the gap and slidinto position around the pole. A second jacket is placed around the polewith its gap positioned 180° around the circumference of the pole fromthe gap of the first jacket. Third and fourth jackets can be placedaround the underlying jackets, with the gap of the third jacket placedat 90° to the gap of the first jacket and the gap of the fourth jacketat 180° to the gap of the third jacket. In order to protect the polefrom heat and fire, a fire-resistant ablative material of knowncomposition, such as iron oxide, can be included in the compositereinforcement members. For example, the fire-resistant material can bemixed in with the resin in the resin bath.

The present invention can also be used in the repair of pilings onwharfs and docks due to either erosion from the sea water or from thebanging of ships. The jackets of the present invention are set in placeusing adhesive. The urethane adhesive systems described above areactivated by water and, therefore, the moisture in the piling does notaffect adversely its adherence. In fact, the water could provide atighter fit for the jacket.

The composite reinforcement members and methods described thus far arewell suited to retrofit existing supports such as concrete columns, aswell as to reinforce newly-constructed supports. By a further aspect ofthe present invention, it is possible to achieve additional saving intime and costs in the construction of new concrete columns. In thisaspect of the present invention, the composite reinforcing isconstructed first as an elongate form. The composite materials which canbe used to construct the form are the same as the materials used in thecomposite reinforcement members described earlier herein. The elongatecomposite reinforcement member has open ends and is secured, usually ina vertical orientation, at the location where the concrete column is tobe constructed. When the composite reinforcement member is secured inplace, concrete is poured into the upper open end of the reinforcementmember in the conventional manner for pouring concrete columns. Ifdesired, steel reinforcing bars can be positioned inside the compositereinforcement member prior to the pouring of the concrete. When thepoured concrete has cured, the composite reinforcement member, whichacted as the form for pouring the concrete, is left in place to providethe reinforcement which the earlier embodiments described hereinprovide. As with the other embodiments, the thickness of the compositereinforcement is determined by the forces expected to be encountered.

As can be appreciated from FIG. 12, the elongate composite reinforcementmember 150 can be made by feeding webs 151 and 152 of bidirectionallyoriented, or tridirectionally oriented, fibers or filaments, through aresin bath to completely impregnate and embed the fibers in a matrix ofthe resin and then removing excess resin. The web 151 is wound helicallyaround an elongate mandrel 154, such as a cylindrical mandrel, in afirst direction, for example at a 45° angle to the longitudinal axis ofthe mandrel, to make a first layer having a cylindrical shape. Thesecond web 152 is wound helically over the first web 151 in an oppositedirection, for example, at a 45° angle with respect to the longitudinalaxis of the mandrel 154, but on the opposite side of the longitudinalaxis from the angle of the first web. Thus, one web is wound at apositive angle with respect to the axis, the next web wound at anegative angle, and so on, so that a herringbone pattern is present. Inturn, the webs 151 and 152 can be attached near one end of the mandreland the mandrel rotated as each web is fed progressively along themandrel to form a continuous helix in which adjacent convolutions of thehelix are in abutment with one another so that no spaces are left in thecomposite member which is being formed. Prior to wrapping the web ontothe mandrel, the mandrel is sprayed with a coating of a release materialso that the completed composite reinforcement member can be slippedaxially from the mandrel after the reinforcement member has been formedand the resin fully cured.

The reinforcement devices of the present invention in the jacket formwere tested on a series of concrete cylinders using the “Standard TestMethod for Compressive Strength of Cylindrical Concrete Specimens” ofthe American Society for Testing and Materials, Designation: C39.Cylinders 1-4 were 6 in. in diameter and about 12 in. long, andcylinders 5-8 were 6 in., in diameter and about 9 in. long. The testcylinders were concrete cores that are ordinarily cast to test thestrength of a concrete batch. Normally, the concrete cores have acompression strength of 4,000 to 6,000 psi.

The test cylinders were reinforced with 4 layers, that is, 4 jackets, ofcomposite reinforcement. The composite reinforcement was adhered to theconcrete column using an expanding urethane concrete adhesive system.

The compression tests had the following results:

Thickness of Total Load Load/Area Test Specimen Reinforcement (lbs)(psi) Cylinder #1 No 170,500  6,030 Reinforcement Cylinder #2 .144″299,750 11,390 Cylinder #3 .184″ 332,260 15,420 Cylinder #4 .216″474,600 17,310 Cylinder #5 No 149,500  5,290 Reinforcement Cylinder #6.140″ 322,100 11,390 Cylinder #7 .180″ 435,900 15,420 Cylinder #8 .216″489,300 17,310

In addition, splitting tensile tests were done on concrete cylindersusing ASTM's “Standard Test Method for Splitting Tensile StrengthConcrete Specimens”, Designation: C 496. This test measures thesplitting tensile strength of concrete by the application of diametricalcompressive force on a cylindrical concrete specimen placed with itsaxis horizontal between the platens of a testing machine. This test isused to evaluate the shear resistance provided by concrete. The testcylinders were reinforced in the same manner as in the compressiontests.

The splitting tensile tests had the following results:

Thickness of Total Load Load/Area Test Specimen Reinforcement (lbs)(psi) Cylinder #9 .140″ 75,880 905 Cylinder #10 .180″ 100,400  1,210 Cylinder #11 .216″ 107,300  1,280  Cylinder #12 No Reinforcement 33,750405 Cylinder #13 No Reinforcement 48,040 560

As can be seen from FIG. 13, in the splitting tensile tests of barecylinders #12 and #13, the concrete failed at 33,750 lbs and 48,040 lbs,respectively, and the vertical compression at the point of the failurefor both bare cylinders was 0.3″. In the splitting tensile test ofreinforced cylinder #10, the concrete failed at a splitting tensile loadof 35,490 lbs., where the vertical compression was at about 0.42″.However, despite the fact that the concrete, that is, the primaryload-bearing member, failed, the reinforced cylinder as a wholecontinued to support even greater loads, up to 100,400 lbs. at avertical compression of about 0.83 inches. Thus, despite the failure ofthe primary load-bearing member, the reinforced cylinder #10 as a wholewithstood almost three times the amount of the force that caused thefailure of the concrete. Similarly, in reinforced cylinder #11, theconcrete failed at 33,620. lbs at a vertical compression of about 0.37inches, but the cylinder failed at 107,270 lbs. at a verticalcompression of about 1.03 inches.

It will be apparent to those skilled in the art and it is contemplatedthat variations and/or changes in the embodiments illustrated anddescribed herein may be made without departure from the presentinvention. Accordingly, it is intended that the foregoing description isillustrative only, not limiting, and that the true spirit and scope ofthe present invention will be determined by the appended claims.

What is claimed is:
 1. A reinforced load supporting structurecomprising: (a) An inner load supporting structure having an exposedperimeter; (b) A first layer around said exposed perimeter of said loadsupporting structure having at least one distinct piece of preformedengineering material having high tensile strength and high modulus; (c)At least one additional layer around said exposed perimeter of said loadsupporting structure and said first layer, having at least one distinctpiece of preformed engineering material having high tensile strength andhigh modulus wherein each piece of engineering material is joinedtogether at at least one joint and wherein said at least one joint on atleast one additional layer is not aligned with said at least one jointon said first layer; and (d) An adhesive substance adhering said layersof at least one distinct piece of engineering material wherein eachpiece of engineering material is preformed with shape complementary tothe exposed perimeter of the load supporting structure.
 2. Thereinforced load supporting structure set forth in claim 1 wherein saidpieces of engineering material are precured composites.
 3. Thereinforced load supporting structure set forth in claim 1 wherein saidfirst layer of engineering material covers less than 360° of saidexposed perimeter.
 4. The reinforced load supporting structure set forthin claim 3 wherein said pieces of engineering material are precuredcomposites.
 5. The reinforced load supporting structure set forth inclaim 1 wherein said pieces of engineering material are arc-shaped. 6.The reinforced load supporting structure set forth in claim 1 whereinsaid pieces of engineering material are angular-shaped.
 7. Thereinforced load supporting structure set forth in claim 1 wherein saidfirst layer is adhered to said exposed perimeter of said inner loadsupporting structure.
 8. The reinforced load supporting structure setforth in claim 1 wherein each layer contains at least two pieces ofengineering material.
 9. The reinforced load supporting structure setforth in claim 1 wherein a distinct first preformed piece of engineeringmaterial is part of said first layer and a plurality of preformed piecesof engineering material are in succession first adjacent to said firstpiece of engineering material and then adjacent to each succeeding pieceof engineering material around said structure and around said first andsucceeding pieces of engineering material.
 10. The reinforced loadsupporting structure set forth in claim 9 therein said pieces ofengineering material form at least two layers and each piece ofengineering material is joined together with each succeeding piece ofengineering material at a joint and wherein each joint on at least oneadditional layer is not aligned with each joint on said first layer. 11.The reinforced supporting structure set forth in claim 10 wherein eachpiece of engineering material covers less than 360° of said exposedperimeter.
 12. A process for reinforcing a load supporting structurearound its exposed perimeter with a pre-cured composite shellcomprising: (a) placing a first layer of at least one distinct precuredcomposite piece around said exposed perimeter of said load supportingstructure; (b) applying an adhesive substance between said piece andsaid structure; and (c) exerting pressure on said shell until theadhesive cures wherein each pre-cured composite piece is preformed witha shape complementary to the exposed perimeter of the load supportingstructure, (d) placing a least one additional layer of at least onedistinct pre-cured composite piece around the exposed perimeter of saidload supporting structure and first layer of at least one precuredcomposite piece and applying an adhesive substance between said layers.13. The process of claim 12 wherein said at least one composite piecewithin the same layer is joined together at at least one joint andwherein said at least one joint on at least one additional layer is notaligned with said at least one joint on said first layer.
 14. Theprocess of claim 13 wherein each layer contains at least two compositepieces.
 15. The process of claim 13 wherein each composite piece coversless than 360° of said exposed perimeter.
 16. The process of claim 13wherein each layer of at least one composite piece covers less than 360°of said exposed perimeter.
 17. The process of claim 13 wherein saidcomposite pieces are arc-shaped.
 18. The process of claim 13 whereinsaid composite pieces are angular-shaped.
 19. The process of claim 13wherein said adhesive substance is applied to each piece prior toplacing said piece around the perimeter of said structure.
 20. Theprocess of claim 12 wherein said first layer of at least one compositepiece covers less than 360° of said exposed perimeter.
 21. The processof claim 12 wherein at least two distinct pre-cured composite pieces ofsaid first layer are placed over a first portion and at least oneadjoining portion of said exposed perimeter over the length of said loadsupporting structure.
 22. The process of claim 12 wherein a distinctfirst precured composite piece is placed as part of said first layeraround said exposed perimeter of said load supporting structure andfurther comprising placing a plurality of pre-cured composite pieces insuccession first adjacent to said first composite piece and thenadjacent to each succeeding composite piece around said structure andsaid first and succeeding composite pieces, and wherein said compositepieces form at least two layers and each composite piece is joinedtogether with each succeeding composite piece at a joint and whereineach joint on at least one additional layer is not aligned with eachjoint on said first layer.
 23. The process of claim 22 wherein eachcomposite piece covers less than 360° of said exposed perimeter.
 24. Aprocess for reinforcing a load supporting structure around its exposedperimeter comprising: (a) placing a first layer of at least one distinctpiece of preformed engineering material having high tensile strength andhigh modulus around said exposed perimeter of said load supportingstructure; (b) placing at least one additional layer of at least onedistinct piece of preformed engineering material having high tensilestrength and high modulus around said exposed perimeter of said loadsupporting structure and said first layer, wherein said at least onepiece of engineering material is joined together at at least one jointand wherein said at least one joint on at least one additional layer isnot aligned with said at least one joint on said first layer; (c)applying an adhesive substance between said layers of at least onedistinct piece of engineering material; and (d) curing said adhesivewherein each piece of engineering material is preformed with shapecomplementary to the exposed perimeter of the load supporting structure.25. The process set forth in claim 24 wherein said engineering materialis a pre-cured composite and said curing means comprises exertingpressure on said layers until the adhesive cures.
 26. A method ofreinforcing a cylindrical support column, comprising: preforming aplurality of reinforcing members each comprising a sleeve terminating inlateral edges next to each other, said sleeve defining a discontinuityat the lateral edges, said sleeve having a plurality of first hightensile strength filaments extending parallel to one another, and aplurality of second high tensile strength filaments extending parallelto one another at a 90° angle to the first filaments, wherein the firstand second filaments are embedded in a matrix of a fully cured resin,wherein the step of preforming comprises forming at least some of thesleeves to have an inner diameter substantially equal to the diameter ofthe cylindrical support column, wherein the step of preforming comprisespreforming said sleeve to have the first high tensile strength filamentscomprise approximately 90% of all of the high tensile strength filamentsof the sleeve and extend parallel to the lateral edges of the sleeve andthe second high tensile strength filaments to comprise approximately 10%of all of the filaments of the sleeve; wrapping the sleeves around thecylindrical support column from one end of the cylindrical supportcolumn to the other such that the sleeves cover substantially the entirecylindrical support column; and fixing the sleeves to the cylindricalsupport column with adhesive.